As the numbers game is in full swing ahead of the July 22 trust vote, CPI(M) on Thursday stepped up the attack on the Congress on the issue of "taking recourse" to convicted Lok Sabha MPs to save the government.

The CPI(M) politburo said there were reports that some of the Lok Sabha MPs who have been convicted for "serious crimes" and who are in jail are being mobilised to support the government in confidence vote.

While legally the convicted MPs may get the right to attend Parliament and vote, "there is a question of political morality involved," the party said in a statement.

"The Congress leadership will be seen by the entire country as taking recourse to convicted criminals for sustaining their government," it said.

The statement pointed out there were three members who were convicted on criminal cases -- Pappu Yadav, Mohd Shahabuddin (RJD) and Suraj Bhan (LJP).

While Yadav has been sentenced to life imprisonment for the murder of CPI(M) MLA Ajit Sarkar, Shahabuddin was awarded life sentence in a case of kidnapping with intent to murder besides facing charges in the case of murder of a CPI(ML) leader Chandrasekar.

Bhan was convicted in a case of murder and sentenced to life imprisonment, the statement said.